There are traditionally two types of line used for wireline operations: so-called slick-line, and twisted conductor cable. In both types the line is fed into the well through a stuffing box with seals. The sealing devices create much friction towards the moving wireline both on its way into and out of the well. Further, the sealing devices are subject to wear and constitute a potential point of leakage from the well to the environment. Further still the sealing device must operate over a given length of the wireline with a rather steep pressure gradient along the given length, thus the sealing device will occupy at least the given length of the pressure gradient.
A winch assembly is described in US20100294479A1 published 25 Nov. 2010. It has a wire winch system subdivided into several chambers and with a direct-drive drum and diamond screw system and provided with a pipe system for the wire extending upwards from the housing to a sheave and down into the center of the housing to the toolstring.